williams



& K WIUJAMS,Jm

CALL DISTRIBUTING SYSTEM. APPLICATION FILED JULY 14,1917.

1 ,3 l Q,226, Putmted July 15, 1919.

4 SHEETS-SHEET 1.

S. B. WILLIAMS, In.

CALL DISTRIBUTING SYSTEM.

I APPLICATION FILED IULY I4. I917. 1510226. Patent-ed July 15, 1919.

' 4 SHEETS-SHEET 2.

S. B. WILLIAMS, IR. CALL DISTRIBUTING SYSTEM.

APPLICATION men JULY 14. 19:1.

1 3 1 @226, Patented July 15, 1919.

4 SHEETS-SHEET 3.

S. B. WILLIAIVIS III.

CALL DISTRIBUTING SYSTEM.

APPLICATION FILED JULY 14. I927.

MK I M MI W 9 '0 Em mm 1W 0 um f M H G8 Q IE4 V n m h R Sdmue/ 5.IVMI/fi STATEfi PATW @Ftfi.

SAMUEL B. WILLIAMS, JR, 0F BROOKLYN, NEW YORK, ASSIGNOE TO WESTERNELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OFNEW YORK.

CALL-DISTRIBUTING- SYSTEM;

Specification of Letters Patent. I Patntedt July 5, 11919.,

Application filed July 14, 1917. Serial Ito. 180,633.

To all whom it may concern:

Be it known that I, SAMUEL B. WILLIAMS,-

J r., a citizen of the United States, residing at Brooklyn, in thecounty of Kings and State of New York, have invented certain theoperators positions that are available.

for receiving them. In complex systems of this character, abnormalconditions sometimes arise that thnd to prevent the proper and promptextending of the circuits of calling lines to the operators positions.It is the principal object of this invention to provide an organizationin which such abnormal conditions, when they arise, will be taken careof and prevented from interfering with the proper operation of thesystem.

Generally stated, the present system provides a plurality of operatorspositions each equipped with a number of plug-terminated connectingcircuits for completing connection with called subscribers lines. Theconnection between these connecting circuits and the calling subscriberslines is effected necting circuit at that position. The selec-' .tion ofan available operators position is controlled by operators selectingapparatus common to all of the finder circuits and all of the operatorspositions.

In the normal operation of the system the potential which identifies anyof the lines as a calling line is automatically withdrawn when thefinder circuit makes connection with that line. If through any fault, ofthe apparatus that potential is not withdrawn, the extension of the lineto an operators position may give rise to diiiiculties. One of theobjects of the present invention is to prevent the line under suchconditions from being extended. Another object is to make thedisconnection of the finder circuit from the calling line subject to thereturn of the connecting circuit to its normal condition so that thefinder circuitmay be held and identified, or a characteristic signalgiven, in case it is not operating properly. Another object of theinvention is to provide means for preventing the finder circuit frompro-,

of the invention is illustrated in the accompanying diagrammatic drawingin which 7 Figure 1 shows two groups of lines with two line finderswitches formaking connection therewith, together with the associatedcircuits and apparatus through the medium of which the lines control theswitches; Fig. 2 shows one finder circuit complete, and enough of twoother finder circuits to illustrate the relationship between them; Fig.3 shows two cord selector switches of one frame with their associatedselection controlling apparatus and circuits, together withsimilarapparatus and circuits for the cord selector switches (not shown)ofanother frame and Fig. 4 shows the position apparatus and one of theconnecting cord circuits of one operators position and indicates theposition apparatus and a connecting cord circuit of another position;also one of the called lines with which the cord circuit may beconnected. The figures taken together, and arranged side by side in theorder indicated by the lines that extend to the margins of the sheets,illustrate as much of a complete organization as is necessary to may belines of the same'sort, similarly equipped and located at the sameexchange; or the lines may be located at different offices. In thepresent instance, the called line shown in Fig. 4 is indicated as beingprovided with connectionsby means of which it may have control overfinder switch'mechanism in the manner illustrated in connection with thelines of Fig. 1. Each group of lines, LG and LG, has associated with itcertain group apparatus consisting of tworelays l9 and 2 1, a commonprotective relay 250, and a timing sequence switch 100. There is alsoprovided apparatus common to all'of the line groups, comprising therelays 22, 23 and 33. a

The groups of lines have access to. groups of connecting circuitsthrough the medium of finder circuits F, F, and F which terminate uponthe brushes of pairs of finder switches of which two sets, LF and GS andLF and OS, are shown. Each of the groups of connecting circuits isassociated with a particular operators position, of which the apparatusof one is shown at O and the apparatus of the other is partially shownat O. In the particular system illustrated, it is the practice toprovide each operators position with twenty-five connectin circuitsextending to multipled groups 0 terminals upon the cord selectorswitches, and to give the brushes of each cord selector switch access tothe terminals of twenty such groups of connecting circuits. But one ofthe connecting circuits is shown complete, the otherconnectlng circuitsin the associated group and in the other groups being similarlyorganized and connected. Multiple connections of the connecting circuitwith the terminals of the cord selector switches are shown. in the caseof the connecting circuit that is completely illustrated; and in likemanner multiple connections of the telephone line with the terminals ofthe line finder switches are shown I in the case of the line thatextends from necting circuits and their corresponding operatorspositions. This is indicated in Fig. 3. Each of the groups of cordselector switches has associated with it certain selection controllingapparatus, that associated with the cord selector switches shown in Fig.3 appearing under the caption Frame 2, and that associated with the cordselector switchesof the other group that is not shown appearing underthe caption Frame 1. The selection controlling apparatus for each frameor group of cord selector switches comprises a set of relays 77, 93 and94: for each operators group, CG, CG, to which the cord selector hasaccess, and a group of relays 52, 5 1, 55, 61, 63 and 254 common to allof the first mentioned groups.

As the line finder switches LF and LF, and the cord selector switches GSand CS" in themselves are not novel, they are shown merelydiagrammatically. These switches may be substantially like the switchillustrated and described in the patent to James L. McQuarrie, No.1,177,044, issued March 28, 1916. The line finder and cord selectorswitches are alike in all substantial 'respects. Each comprises alongitudinally movable shaft 1 carrying as many sets of brushes 2 asthere are groups of stationary terminals to be engaged. To move theshaftup, an extension at the lower end of the shaft is brought intoengagement with the constantly rotating power member 3 by means of anidler wheel operated by the updrive magnet 32; and to move the shaftdown, the'extension is brought into engagement with the power member 4by means of an idler wheel operated by the down-drive switch shafts 1and carries as many tripping yokes 7 as there are finder switches in thegroup. The trip rod, in rotating, brings all of its tripping yokes 7into position to operate the brush controlling cams 5 of thecorresponding sets'of brushes on all of the switches, so that whicheverof the finder switches is caused to move up, has that set of brushestripped that corresponds with the particular trip magnet 16, 17, that is'at the time energized. When the finder switch that has been in use isreturned. to its normal positlon, any of the associated controlling cams5 that has been tripped is engaged and rotated in a reverse rection toseparate its switch springs again and thus renary commutator segmentsand a set of mov-' able brushes carried at the top of the switch shaft 1and cooperating with the stationary segments. This commutator serves tomakeand break a number of controlllng ClI'CllltS' in the various stagesof the upward movement of the switch shaft.

For controlling the circuits of the organization, there are employed anumber of sequence switches which are shown at different points and aredesignated 100, 200, 300 and 400, respectively. These sequence switchesmay be of the type disclosed in Patent 1,127,808, issued February 9,1915, to Reynolds and Baldwin. Each consists of anelectromagneticallycontrolled motor or driving mechanism 1 and a numberof associated switch cams. The switch cams associated with each of thesequence switches 100 are designated 101 to 103 inclusive; thoseassociated with each of the sequence switches 200 are designated 201 to224:inclusive,;..those.associated with each of the sequence switches 300are designated 301 to 304 inclusive; and those associated with each ofthe sequence switches 400 are designated 401 to 413 inclusive. To eachof the contacts associated with the various sequence switch cams areapplied certain numerals. These numerals 1n the case of the cams 101,20-1 301 and 401 indicate the only positions of the associated sequenceswitch in which these particular contacts are open; the numerals appliedto all of the other contacts of eachrsequence switch indicate the onlypositions of the par.- ticular associated switch in which the associatedcontacts are closed.

The sequenceswitches 100 merely act as timing switches and have only oneresting position. The resting positions of the other sequence switches,and the stages of operation with which these positions are associated,are as follows:

Sequence switch 200.

s wr Sequence switch 300.

1. Awaiting a call. 4. Position vacant. 17. Position busy.

Sequence sioz'tch 400.

1. Normal. 7. Listening in. .15. Listening out.

I The manner in which the system is or.- ganized will appear from thedescription of its operation which follows. sumed that the subscriber atstation A initiates a call. \Vhen the telephone receiver is taken fromthe switchhook, a circuit is closed that extends by way of both windingsof the line relay 12 and both limbs of the telephone line, and iscompleted in the contacts of the switchhook at the subscribers station.The flow of current in this circuit energizes the line relay 12, whichin operating applies at its right -hand armature and contact, a groundto the conductor 18. This causes current to flow from battery throughthe winding of the relay 19, sequence switch contact 103 (18% to 11;),conductor 18 and ground at the contacts of the operated line relay 12.The relay 19 attracts its armature and closes a circuit that extendsfrom battery through the right-hand winding of the associated relay 24,front contact of relay 19, back contact of relay 22 and lower armatureand back contact of relay 23 to ground. Relay 24 operates and closes inits left hand front contact a circuit that extends from battery by wayof the winding of the associated group. tri magnet 16' and the left-handwinding 0 the relay 24, in parallel, to the front contact of that relay,and thence'by way of conductor 58, the winding of the relay 22, and thelower armature"and back contactof the relay 23 to ground.

.- -Current flowing in the circuit'traced above operates the trip magnet16 of the group in which the calling line is located, locks up the relay.24 of the associated group and operates the relay 22 common to all ofthe groups. The trip magnet 16 rotates its associated trip rod to bringall of the yokes into position to trip the corresponding set of brushesof whichever of the line finder switches is started. The group relay--24breaks, in its left-hand back contact, the circuit of the conductor 58to the corresponding relays 24 of the succeeding groups of the series.

The relay 21, in its right-hand front con tact, also completes a circuitthat extends from battery through the motor magnet of the sequenceswitch 100, and contact 102 (18% to 1%) of that switch. In moving out ofposition 1, sequence switch 100 closes its contact 101 and opens itscontact 103 after leaving position 1-1. As contact 101 is closed in allpositions excepting position 1 of the It will be asone completerotation; and as contact 103 sequence switch, the switch is caused tomake of the sequence switch is open in all positions exceptingpositions18% to 11, the 'con- "ductor 18is held openwhile the sequence switch ismaking its revolution'anduntil it gets backto position 1.- The timerequired by the sequence switch-to make one complete rotation is soregulated as to be greater than that-occupiedby the line finder switchin finding the terminals of any calling line. The action, therefore, issuch as to interrupt the group conductor '18, and hold it open untilafter the line relay 12 of the calling line has been released as aresult of the finding of that line.

- -'and.the tripping of only one set of brushes on a started line finderswitch.

The common relay 22, when it operates,

.applies ground to the starting conductor 29 to start a finder switchhunting for the calling line. The startin conductor 29 has branchesextending to 1i e sequence switch cams 206 of all of the finder circuitsterminating upon the line finders that have access to the .calling line.But, for reasons which will hereinafter be explained, the sequenceswitch 200 of only one of these finder circuitsis standing in its 2position. Assuming that this is the sequence switch offinder circuit F,when the relay 22 is actuated by the calling line, as already described,a circuit is completed that extends from battery through the left-handwinding of relay 30, sequence switch contacts 206 (2), conductor 29,front contact and armature of starting relay 22, lower armature and backcontact of relay 23 to ground. The right-hand winding of relay 30 is atthis time also included 1n parallel with the lefthand windin of therelay inthe energizing circuit, t e parallel branch being from batterythrough resistance'coil 56, sequence switch contact 217" (2 to 9)right-hand winding of rela 30, sequence SWltChtOl'ltacts'220 (2) an (1to 13),thereaiter joinin thev conductor that extends from the le t-handwinding of relay 30, and to ground over the circuit already traced. Theeffect of this is to give the relay 30 the benefit of the energizingaction of both windings.

As a result of the closure of the circuit traced above, the relay 30 isenergized and closes a circuit that causes the associated sequenceswitch 200 to move out of position 2. This circuit extends from batterythrough the motor magnet of the sequence switch 200 sequence switchcontact 202 (2), right-hand front contact and armature of relay 30,sequence switch contact 208 (2 to sequence switch contacts 216 (2 to 4)and (2 to 9),front contact and left-hand armature of the relay 30, andarmature and back contact of the relay 37 to' ground.

As a result of the closure of its motor magnet circuit in the right-handfront contact of the relay 30, the sequence switch 200 moves out ofposition 2 and comes to rest in position 3. In position 3 of the switch,a circuit is closed that extends from battery by way of-the up-drivemagnet 32 of the corresponding line finder switch LF, conductor 59,sequence switch contact 207 (3 to 4), front contact and right-handarmature of rela 30, sequence switch contact 208 (2 to 7 and to groundby way of conductor 79 and the commutator segment M and associated brushof the corresponding cord finder CS. The energization of the up-drivemagnet 32 starts the upward movementof the corresponding elevator rodwith its associated sets of brushes. At the outset of the upwardmovement of the elevator rod, all of the brush trip levers are movedpast the corresponding trip yokes. The only trip magnet that isenergized in this case is the magnet 16 which corresponds with the groupin which the calling line is located; and, consequently, the only tripyoke in position to engage a tri lever on the elevator rod is the onewhic controls the brushes 40, 41, 42 and 43 that are adapted to engagethe terminals of that particular group of lines. This set of brushes,therefore, is released and made operative and the other sets are heldclear of their associated line terminals.

As soon as the set of brushes correspond- 7 sequence switch contact 209(2% to3), con- '16, the group relay 2% and the common starting relay 22.Relay 23, at its upper front contact, closes a locking circuit foritself and the associated relay 33 that extends by way of conductor 25-and the sequence switch contacts21Q (2% to 1) of all of the findercircuits in series, to ground at a point beyond the last switch-of theseries.

As has already been stated, normally there is only one of the findercircuits .with its sequence switch in the receipt of a call. When thecall comes in, this sequence switch is immediately moved to position 3,in the manner-described above. Therefore, at this stage of theoperation, thesequence switches of allof the finder circuits arev inposition to close their contacts 210. The locking circuit for the relays23 and33 is, therefore, held closed un til another one of the findercircuits has its sequence switch moved into position 2.

This is accomplished by relay 33, which, in

operating, applies a ground to conductor 28 to move the sequence switchof another finder gircuit out of position'l and into position u, andwhich alsoapplies a ground to the conductor 27 to move' the sequenceswitch of the appropriated finder circuit out otposition 3.

Assuming that the sequence switch of finder circuit F is in position 1and that the sequence switch of finder circuit F is in some positionbetween 4 and 17, that findeip' circuit being assumed to be in use, theop eration of the relay 33 completes the 'following circuit: frombattery, through the motor magnet and contacts 203(1) of the sequenceswitch of finder circuit F, contacts 211 (1) of the same sequenceswitch, contacts 211 (3 to 17) and (4 to 17) of the sequence switch 200of finder circuit F contacts 211 (3 to 17) and (3 to 3}) of the sequenceswitch 200 of finder circuit F, conductor 28, lower contact and armatureof the relay 33 to ground. This causes the sequence switch of findercir-' cuit -F to move into position If by any chance the Sequence switchof finder circuit F should fail to be moved into the call-awaitingposition 2 when the relay 33 operatesit will be moved into that positionwhen the sequence switch of the appropriated finder circuit F moves intoposition 5 at a slightly later stage in the operation. The circuit bywhich this result would, under the circumstances, be accomplishedextends from battery through the motor magnet and posit-ion 2 awaitingcontact 203 (1) of the sequence switch-of finder circuit F, contacts 211(1) of that sequence switch, sequence switch contacts 211 (4 to 17) and(3 to 17) of finder circuit F 2 (assumed to be in use), and thence byway of contacts 222 (5 to 1) of all of the finder circuit sequenceswitches in series to ground. I n other words, at any time that thefinder circuit sequence switches are all ,standing in position 1 or inposition 5 and beyond, a ground is applied by way of the I 222 cams inseries-that moves one of the switches into position 2, and thus placesthe associated finder circuitin its call-awaiting condition. Thesequence switch of finder circuit F is moved out of position 3 by theclosure of a circuit that extends from battery through the motor magnetand contacts 203 (-3) of the sequence switch of that circuit, conductor27 and upper contact and armature of relay 33 to ground, As soon, as thesequence switch of finder circuit F moves into position 2, it opens atits contacts 210 the circuit by way of conductor 25 which has beenmaintaining relays 23 and 33 energized, and these relays release theirarmatures. Relay 23, in releasing, reconnects to ground the circuitwhich'extends in branches 57 and 58 through its Various Sets of grouprelays, thus again giving the groups access to the starting circuit. l

At this stage of the operation of the systeui, the sequence switch ofthe appropriated finder circuit F is in position 4, and the elecallingline is located. As the tripped brushes rise. they come into engagementsuccessively with the sets of contacts corresponding with the differentlines of the oup. At the inst-ant of engagement of the rush-43 with theterminal 47 of-each line, the test relay 37 of the finder circuit isconmated with local conductor 2530f that line.

This local conductor has two branches, one or the other of whlchisclosed depending upon. the condition of the line relay 12. of theassociated line. If the line relay inert, as it is when the line is notcalling, or when the. line has beenconneotecl with and its cutoff relayoperated, the local conductor 253 of the line is connected with'gnoundby way of an identifying device 252 and-fa relatively low potentialbattery. If the li elay 12 is energized, as it is when the linev llingand is not connected with, the local onductor 253 of the line isconnected withfground by way of the right-hand back contact and armatureof the protective relay 250. common to a group of lines, the energizingwinding of this relay, and a relatively high potential battery 251.Therefore, as the elevator rises. and the brush 43 engages thecorresponding terminal 47 of each of the lines of the group in which thecalling line is located, a circuit is completed as each line terminal isengaged that extends, either by way of the low potential battery, thedevice 252, and the lefthand back contact and armature of relay 12 tothe local conductor 253 of the line; or by way of the high potentialbattery, the winding of common relay 250, the right-hand armature andback contact of that relay, and the left-hand front contact and armatureof relay 12 to the local conductor 253; and thence by way of lineterminal 17, brush 43, conductor 51, finder sequence switch contacts 224(l to 8) and (2+1: to 4), and winding of relay 37 to ground.

The relay 37 is so adjusted that it will respond only to the currentflow produced in the circuit of the high potential battery, and not tothat produced bythe low potential battery. As the line relay 12 of thecalling line is energized, thus connecting the high potential battery tothe associated local conductor 253, the test relay 37 responds when thebrush 43 engages the terminal 17 of the calling line. The response ofthe relay 37 causes that relay to interrupt in its back contact thepreviously traced circuit by way of the left-hand armature and frontcontact of the relay 30, sequence switch contacts 216, and right-handwinding of relay 30, which circuit had been holding the relay 30 lockedup from the moment that the relay was first energized upon the receiptof the call. Relay 30 in releasing its armatures breaks its own lockingcircuit, and also breaks the previously-traced path, including sequenceswitch contacts 208, right-hand armature and front contact of the relay30,-and sequence switch contact 207, over which current has been flowingto energize the up-drive magnet 32 of the line finder. Therefore, theoperation of the relay 37 upon the finding of the call-' ing line actsto effect the instant deenergization of the up-drive magnet 32, and thusto stop the brushes upon the terminals of the calling line.

In order that the brushes may always be stopped in registration with theline terminals, the locking circuit of the relay 30 has an alternativepath to ground by way of sequence switch contact 215 (2 to 4:),conductor 66, the C segment of the line finder commutator and thecorresponding brush to ground. The C segment of the commutator is soformed and related to its brush that the connection between the two isinterrupted only when the corresponding line brushes on the elevator rodare in engagement with corresponding sets of line terminals. Theunlocking of the relay 30, and the consequent stopping of the upwardmovement of the elevator rod, can therefore occur only when the linebrushes are in proper relation to the terminals of the calling line.

When the relay 30 is denergized, as a result of finding the callingline, it also completes a circuit that extends from battery through themotor magnet and contact 202 (3 to 1) of the finder sequence switch,righthand back contact and armature of the relay 30, sequence switchcontact 208 (2 to 7), conductor 79, and M segment andcorresponding'brush of the cord selector OS to ground. The closure ofthis circuit moves the sequence switch out of position 4.

When the finder sequence switch reaches position 4%, it closes a pathfor the flow of current through the cut-ofi relay 11 of the calling lineby way of resistance coil 61, sequence switch contact 212 (4% to 12%),con ductor 50, crush 42, line terminal 46 and conductor 53." The flow ofcurrent in this circuit operates the cut-off relay 11 to disconnect therelay 12 from the circuit, and that relay in releasing its armaturesdisconnects the high potential test battery from the local conductor 253and disconnects ground from the common conductor 18.

The disconnection of ground from conductor 18 occurs before the timingsequence switch 100 has completed its cycle of rotation and reconnectedconductor 18 with relay 19. T I

The brushes of the line finder switch are now at rest in engagement withthe terminals of the calling line, the sequence switch 200 of findercircuit F is at position 6, the group starting circuit represented bythe conductors 57 and 58 and the associated. relays 22, 23 and 33 hasbeen released and is in readiness to respond to another calling line,and the sequence switch of another finder circuit has been moved intoposition 2, and thus brought into operative relation with the startingconductor 29.

When the sequence switch of the finder circuit over which the call isbeing extended has reached position 6, the finder circuit is broughtinto operative relation with the operators selecting circuit. When thefinder sequence switch reaches position 6, it awaitsthe closing of acircuit, the completion of which is dependent upon the condition of theother finder circuits of the associated group. This circuit extends frombattery through the left-hand winding of the relay 30, contact 219 (6)of the appropriated circuit sequence switch. contacts 219 (9 to 4) f thesequence swit hes of the associated nder circuits preceding it in theseries, conductor 76, outer armature and back contact of relay 54, andright-hand back contact and armature of relay 61 to ground. A branchpath for the energization of relay 30 also exists at this time, thisbranch path extending t'ronibattcry through resistance 56. sequenceswitch (Olll'tl'iS 217- (9 to 9), right-hand winding of rclav. 30.

ated finder circuit sequence switch, from which point it extends toground at the right-hand 'back contact and armature of the relay 61overthe path'already traced. This circuit for the energization of relay30 is open either in the cam 219 of a preceding finder sequence switchin the series, or in contacts of the relay 54 or 61 as long 'as anysequence switch'of the series tions 4 to 9. That is, it is open time theline finder switch of is in po'sifrom the any assoc1- ated findercircuit finds a calling line until the cord finder switch of thatcircuit has moved far enough to trip the brushes corresponding with theselected operators position, as will be described. Not until this hasoccurred will the above traced circuit of the awaiting finder circuit beclosed. When the circuit is closed, the relay 30 attracts its armaturesand completes a circuit that extends from battery through the motormagnet and sequence switch contact'202 (6 to 7) .of the sequence switch200, righthand front contact and armature of relay 30, sequence switchcontact 208 (2 to 7), conductor 79, and segment M and correspondingbrush of the cord selector commutator to ground. The completion of thiscircuit moves finder sequence switch out of position 6.

When the sequence switch 200 reaches position 6?; it closes a circuitthat extends from battery y way of the winding of relay 55 (Fig. 3),conductor 71, sequence switch contact 218 (6% to 8), conductor 67, andsegment M and corresponding brush of the line finder commutator to ound.The operation of the relay 55 applies ground to the conductors 81extending to all of the operators positions. At each" of the positionswhere the operator is at her station and is in readiness to receive acall, the associated relay 91' (Fig. 4) is inert, and theoperatorstelephone sequence switch 300 is in its 1 position.Consequently at each of such positions, a circuit is closed that extendsfrom battery, through the winding of the associated relay 92, lefthandarmature and back contact of relay 91, sequence switch contact 304 (1),conductor 81, armature and front contact of relay 55 to ground. Therelay 920i each awaiting position therefore attracts its armatures andcloses a circuit that extends from battery, through the front contactand armature of the relay 92 to the conductor 82, and thence to groundbyway of the windings of the relays 77 corresponding to that operatorsposition at the various cord selector frames.

When the finder sequence switch 200 1 reaches position 7, in whichposition it comes to rest, it closes a circuit that extends frombatterytbrough the winding of relay 54, lefthand back contact andarmature of relay 61, conductor 73, finder sequence switch contact and94 are energized 218 (7 to 8), conductor 67, and segment M andcorresponding brush of the line finder commutator to ground. Relay =54attracts its armatures and completes a branch of the circuit tracedabove, which branch extends from conductor 73 by way of the armature andback contact of the relay 63, front contact and inner armature of relay54, righthand armature and back contact ofrelay 52, armature and frontcontact of relay 77 (which relay is energized, as previously described,as a result of the corresponding operators position being in readinessto receive a call), right-hand backcontact and switch spring of relay 93of the corresponding group, winding of associated relay 94, winding ofrelay 93, left-hand switch spring and resting contact of relay 93,conductor 83, left-hand back contact and armature of relay 95 at the Ooperators position to battery. Upon the closure of the above-. tracedbranch circuit, group relays 93 in parallel with the relay 54. Relay 93in operating disconnects its own energizing winding and that of relay 94from the previously traced path to battery by way of the left-hand backcontact and armature of relay 95,- and connects them in a path whichextends to battery by way of conductor 84 and the winding of the relay95. This causes the relay 95 also to be energized and to interrupt inits left-hand armature and back contact the path by way of conductor 83over which the relays 93 and 94 were initially energized.

Relay 94 in operating closes a circuit from battery through the windingof the trip magnet 20 corresponding to the selected operators position,and to ground by way of the right-hand armature and front contact of therelay 94. This relay also closes a circuit that extends from batterythrough the winding of the relay 63 and the left-hand ar-' mature andfront contact of the relay 94 to ground. The relay 63 in operatingcloses a branch that extends from the conductor 73 (grounded by way ofcontact 218 (7 to 8) of the line finder sequence switch) throughthe'armature and front contact of relay 63, back contact and armature ofrelay 254, conductor 72, sequence switch contacts 220 (7) and (1 to 13),and left-hand winding of relay 30 to batter A branch energizing path forrelay 30 also extends from conductor 72 by way of sequence switchcontacts 220 (7 right-hand winding of relay 30, sequence switch contacts217 (2 to 9), and resistance 56 to battery. Relay 30 attracts itsarmatures and closes a circuit that extends from battery through themotor magnet and sequence switch contact 202 (6 to 7), front contact andright-hand armature of relay sequence switch contact 208 (2 to 7),conductor 7 9, and segment M and corresponding brush of the cordselector commutator to ground. .The closure of this circuit movessequence .switch 200 out of position 7. Furthermore, relay 30 inoperating is locked up over a circuit that extends from battery throughresistance 56, sequence switch con tacts 217 (2 to 9) right-hand windingof relay 30, sequence switch contacts 216 (7 to 9) and (2 to 9), frontcontact and left-hand armature of relay 30 and armature and back contactof relay 37 to ground.

When the sequence switch reaches position 8 it closes a circuit thatstarts the upward movement of the brush-carrying rod of the cordselectorswitch, this circuit extending from 'battery through the up-drive magnet34 of the cord finder, conductor 89, sequence switch contact 207 (8 to9), right- 'hand front contact and armature of relay 30, sequence switchcontact 218 (8 to 9), conductor 67, commutatorsegment M of the line trolof a s 0w releasing relay 254. The energizing winding of the slowreleasing relay 254 is in parallel with the energizing winding of therelay 54, and the relay 254: is consequently energized by way ofconductor 73 and cam 218 of the finder sequence switch when the sequenceswitch reaches position 7. The energizing path of the relay 254' is byway of the back contact and armature of relay 63, and the armatureandback contact of relay 254: controls the path to relay 30 by way ofthe conductor 72, holding this path open as long as the relay 254 isenergized. \Vhen therefore the actuation of one of the relays 94coperates the relay 63, the operation of the relay 63 does not instantlyclose conductor 72 to energize relay 30 and move the finder sequenceswitch to position 8 where the upward movement of the cord selectorbrushes is started. Instead, the closure ofthis energizing path forrelay 30 is delayed until the relay 254: has had time to denergize,after the interruption of its circuit at the back contact of relay 63,and release its armature to close the path of conductor 72. Undercertain special circumstances in the operation of the operatorssele"ting apparatus it is possible for the trip n'agnets associated withtwo operators positions on the same cord selector frame, or for two tripmagnets associated with same operators position upon two differentframes, to be momentarily operated. By providing the slowacting relay254 for delaying the advance of the finder sequence switch to its nextstage,

the possibilitv of one finder circuit selecting two operators positions,or of two finder circuits on different frames selecting the sameoperators position, is prevented.

At the outset of the upward movement of the cord finder brush rod, thetripping levers of the various sets of brushes are broughtsimultaneously into operative position with respect to the correspondingtrippingyokes, and that set of brushes is tripped and made operativewhose trip magnet is at the time energized. In the present instance, itis assumed that this is the trip magnet 20 associated with the terminalsof the group of connecting cord circuits extending to the O operatorposition.

Immediately after the set of brushes is tripped, the common operatorsselecting circuit is restored so as to be available for the use of othercord finder switches. This is effected through the medium of a circuitthat is completed by the grounding of the K segment of the cord findercommutator, this segment being so located as to be engaged by its brushimmediately after the tripping levers of thesets of brushes pass theassociated tripping yokes. The circuit referred to extends from batterythrough the winding of relay 6'1, conductor 7 41, sequence switchcontact 221 (75} to 8), conductor 80, cord finder commutator segment Kand its corresponding brush to ground. Belay 61 in operating '0 ens, atits left-hand back contact, the prevlously-traced circuit by way ofconductor 73 which, up to this time, has been holding energized therelay 95 atthe O operators position and the relays 93 and 9%corresponding to this position on the cord finder frame. The release ofthe relay 91 del'nergizes the 7 corresponding trip magnet 22 and thecommon relay 63. The deenergization of the relay 93 restablishes,subject to the release of relay 61, the control of other finder circuitsover the brush tripping mechanism of the associated cord finder frame.

Relay 61, in operating, closes a locking circuit for itself by way ofconductor 73, sequence switch contact,218 (7 to 8), conductor 67,commutator segment M of the line finder and corresponding brush toround. It also completes a circuitthat extends from battery through themotor magnet and contact 20l (8) of the sequence switch 200, conductor75, right-hand front contact and armature of relay 61 to ground. Theclosure of this circuit moves sequence switch 200 cut of position 8. Inmoving out of position 8, the sequence switch opens its contacts 218 (7to 8), thus dei nergizing relay 61 and again extending cond'uctor73 tothe relay 54 and the conductors over which the oper: ators selection-iseffected. In closing its right-hand 'back' contact upon release, relay61 also restores the continuity of conductor 76 and makes it availablefor moving out of position 6-the sequence switch of some other throughthe motor magnet and cam 403 (1) finder circuit which may be waiting'foracof the listening key sequence swltch and cess to the operatorsselecting circuit.

After the cord selector switch CS passes the brush-tripping position, itcontinues its upward movement until the brushes are stopped by engagingthe terminals of one of the connecting circuits that is not in use. Theidle or busy'condition of the connecting circuit is indicated by thepresence or absence of high-potential batteryon the test terminal 118 ofeach connecting circuit.

When the brushes engage the terminals of an idle connecting circuit,-,-apath for the flow of current is completed from high-potentialbattery 251 (see Fig. 4), through the winding of common protective relay258, armature and back contact of that relay, lower back contact andarmature of relay 259, conductor 128, armature and back contact of relay420, contact 406 (1) of the listening key sequence switch, conductor 88,test terminal 118 and brush 114 of the cord selector, conductor 99,finder sequence switch contacts 206 (8 to 9) and the Winding of relay 37to ground. .Relay 37 thereupon attracts its armature and opens thepreviously traced locking circuit that has been holding relay 30energized. Relay 30, in releasing its armatures, opens at its right-handfront contact and armature the'energizing circuit for the up-drivemagnet 34, thus stopping the brushes of the cord selector switch inengagement with the terminals of the selected connecting circuit. Inengaging .its back contact, the right-hand armature of relay 30 closesan energizing circuit for the motor magnet of the finder sequence switchwhich extends by way of cam 202 (8 to 9), back contact and right-handarmature of relay 30, cam 218 (8 to 9), conductor 67, and the M segmentand corresponding brush of the line-finder commutator to ground; Theclosure of this circuit moves sequence switch 200 out of position 9,whereupon the switch continues to move until'it reaches position 14,where the talking circuit is completed at cams 213 and 214. l v Aninstant after the finder sequence switch leaves position 9, it closes acircuit that ex tends from battery through the windings of relays 421and 423 (see Fig. 4) in parallel,

listening key'sequence switch contacts 407 (1), left-hand back contactand; armature of relay 422, conductor 87, cord selector switch terminal117 and corresponding brush 113, conductor 98, and finder sequenceswitch contacts 217 (9} to 14) and (9?;- to 11) to ground. Relay 421 inoperating closes a locking circuit for itself and relay 423 that extendsby way of its upper front contact and armature, and sequence switchcontact 405 (1 to 6) to ground. Relay 421 also closes a circuit thatextends from battery open the test conductor 88 at sequence switch.

Contact 406 (l) and also to open at sequence switch contact 407 (1) thepath over which the" relays 421 and 423 were first energized. Relay 423,associated withrelay 421, in operating closes a circuit that extendsfrom battery through the .winding of relay 422 and upper front contactand armature of relay 423 to ground. As a result relay 422, prior to themoving of the listening key sequence switch out of position 1, hasdisconnected conductor 87 from connection with batter by way of sequenceswitch contact 407 (1' and the windings of relays 421 and 423, and hasconnected it with an alternative'path to battery'by way of the left-handfront conrelay 259, conductor 129, and lower front contact and armatureof relay 423 to ground. Relay 259 in operating opens at its lowerarmature and back contact the circuit over which the potential of thehigh voltage test battery 251 is supplied to the test conductors 128 ofall of the connecting cords of the position. Thus the electricalcondition which permits a connecting cord to be seized by a cordselect-or is withdrawn from the selected cord and also from itsassociated cords at the instant of seizure, and is not reapplied to suchof the cords as may be in COIldltlOIL to be selected untiluthe commonrelay 259 is deenergized. The deenergization of relay 259 occurs whenthe relays 421 and 423 are released by the opening of their lockingcircuit at cam 405 when the listening key sequence switch moves beyondposition 6. 7

When the listening key sequence switch 400 is moved out of position 1,in the manner described above, it continues its movements until itreaches position 7. In position 7 the cams 408, 409, 410 and 411 of thelistening key sequence switch interrupt the talking strands of theconnecting circuit and include between their severed ends a loop thathas switch contact 113 (7), and interrupter 162 to ground.

At this particular time the operators sequence switch 300 is in position17 or moving to that position. When the position was selected theoperators sequence switch was standing in position 1 and the relay 91was inert, thus providing a path for the energizatlon of the relay 92,the operation of which relay when an operators posltlon is to beselected serving to mark that particular position as being unengaged orselectable. Then the position is selected, the relay 95 is operated inthe manner previously described. In operating, the relay 95 closes acircuit that extends from battery through the motor magnet and cam 302(1) of the operators sequence switch, right-hand front contact andarmature of relay 95, and right hand front contact, and armature ofrelay 125 to ground. The relay 125 at this time is operated, as itsenergizing path is completed by way of local contacts 127 of theoperators telephone jack 126-, which contacts are closed when theoperator is at her position and has her telephone plug inserted in thetelephone jack. As a result of the closure of the circuit traced above,the operators sequence switch 300 is moved out of position 1, thus ofrelay 92 in sequence switch contact 303 (1) and making the positionunselectable. The next resting position of the, operators telephonesequence switch 300 is position 4:; but as relay 125 is' energized, themotor magnet has an energizing circuit in this position by way ofsequence switch contact 302 (1) and the left-hand front contact andarmature of relay 125 to ground, and consequently the sequence switchmoves on to its next resting position 17. The sequence switch remains inposition 17, keeping the operator position unselectable, until at alater stage in the operation the switch 192 is operated in any suitablemanner to close its contacts. At this time a circuit is closed thatextends from battery through the motor magnet and cam 302 (17) of theoperatorfs telephone sequence switch and closed contacts of switch 192to ground. The closure of this circuit permits the sequence switch tomove from position 17 to position 1, thus rendering the operatorsposition again available for receiving calls.

The opcrators posltion is also rendered unsclectable when the operatorstelephone set is connected with one of the connecting circuits. This iseffected through the meopening the energizing path...

dium of the relay .91. WVhen the listening key sequence switch 400 ofany of the connecting circuits of the operators position is moved toposition 7 to bring the operators telephone set into connection with thecorresponding circuit, an energizing path is completed that extends frombattery through the winding of relay 91, conductor 137, and listeningkey switch contact 404C (2 to 9) to ground. The completion of thiscircuit causes the relay 91 to attract its armature and interrupt thepath over which the relay 92 is adapted to be energized, thus preventingthe operation of the associated selection controlling relays 7 7.

The removal of the telephone plug from the operators telephone jack 126when the operator leaves her position, also renders the positionunselecta-ble. When the plug is removed, the breaking of the circuit atthe local contact 127 causes relay 125 to become inertand release itsarmatures. This closes a circuit that extends from battery through themotor magnet and cam 302 (1) cf the operators telephone sequence switch,and to groimd by way of the left-hand back contact and armature of relay125. In moving out of position 1 as the result of the closure of thiscircuit, the sequence switch interrupts the energizing path for therelay 92 in sequence switch contact 303 (1), thus preventing theoperation of the corresponding selection controlling relays 7 7 when aconnection is to be extended.

Reference has heretofore been made to the operation of the common relay259 which is energized to remove the test condition from the selectedconnecting cord and all of its associated connecting cords at theinstant the cord is seized. This relay when it operates, also acts tocomplete a circuit that extends from battery through the winding ofrelay 91 and the-winding of relay 193 in parallel, and thence to groundby way of the upper front cont-act and armature of relay 259. Relay 193in operating, closes a circuit, from battery through the motor magnetand contact 304 (1) of the operators telephone sequence switch, andfrontcontact and armature of relay 193 .to ground. The closure of thisclrci'ut safeguards the operators telephone sequence switch fromstanding or stopping in position 1 from the instant the cord circuit isseized. Relay 91 in operating insures the inaccessibility of theoperators position at this time by opening the path over whch relay 92must be energized.

When the operator has been put into communication with the callingsubscriber by the movement of listening key sequence switch 400 toposition 7, as already described. and when the operator has learned thenumber of the line that is wanted, the connection may be completed byinserting calling plug 425, in which, in the present instance, theconnecting circuit is represented as terminating. into the spring jack14 of the called subscribers line. Instead of a plug and spring jack,any other of the well-known switching devices or mechanisms .forestablishing connection between a connecting clrcult and a telephone11118 may and may operate in the usual way, a description of them and ofthe exact manner in which the cord circuit is organized is thought to beunnecessary.

When the calling plug 425 is inserted in the called line spring jack, anenergizing circuit is completed that includes serially the windings ofthe connecting cord relays 420 and 431 and the cut-off relay 11 of thecalled line. The cut-ofi' relay 11 may have its usual function ofdisconnecting the line relay 12 thus depriving the line of control overthe calling apparatus. The relay 420 in operating interrupts at anotherpoint the path of the test conductor 88, thus keeping the cord circuitnnselectable while the plug 425 is in the spring jack of the calledline.

The relay 431 at its left-hand back contact breaks the connection of thetip of the plug with the conductor 133, which may extend to the testwinding of the operators telephone set. and atits left-hand frontcontactcloses the tip strand of the connecting cord to complete the talkingcircuit. The relay 43] in operating also closes a circuit that extendsfrom battery through the winding of the relay 500 and the right-handfront contact and armature of relay 431 to ground. The relay 500 at itsouter armature and back contact interrupts the circuit of the flashingcall lamp 161; and extinguishes the lamp. At its inner armature andfront contact, the relay 500 closes a locking circuit for the holdingrelay that extends by way of the right-harid front contact and armatureof that relay. The relay 500 also closes a circuit that extends frombattery through the motor magnet and contact 402 (7) of the listeningkey sequence switch, outer lefthand front contact and armature of relay500, and right-hand back contact and armature of relay 421 to ground,the relays 421 and 4.23 having been released by the opening of theirlocking circuit at cam 405 when the listening key sequence switchmoved'bcyond position 0. The listening key sequence switch moves out oflistening-in position 7 as a result of the closure of this last mentheirarmatures.

tioned circuit, and comes to rest in posi tion 15.

The termination of the conversation between the subscribers is indicatedin the usual way by signals displayed when the supervisory relays 427and 428 become inert, and disconnection is effected by withdrawing thecalling plug 425 from the spring jack 14 The withdrawal of the callingplug 425 interrupts the energizing circuit of the relays 431 and 420,and these relays release The relay 431 in releasing breaks theenergizing circuit of the relay 500, and that relay in releasing closesa circuit that extends from battery through the motor magnet and cam(15) of the listening key sequence switch outer left-hand in releasing,breaks the connection of con-- ductor 87 with battery by way of thedevice 424. Q When current ceases to flow through conductor 87, therelay 30 of the finder circuit, which has been included in the path ofcurrent flow by way of conductors 8T, 98, 50 and 53, and the findersequence switch cams 217 and 212, releases its armatures. This closesthe circuit from battery through motor magnet and cam 202 (14) of thefinder sequence switch, left-hand back contact and armature of relay 30,and armature and back contact of relay 37 to ground. This moves thefinder sequence switch out of the talking position 14.

When the finder sequence switch reaches position 15 a circuit is closedfor the energization of the relay 30 that includes in parallel branchesboth windings of that relay. One branch of this circuit extends frombattery through resistance 56, sequence switch contacts 217 (15 to 16)and (12 to 16) righthand winding of relay 30, sequence switch contacts220 (15) and (11. to 16) to conductor 67; theother branch extends frombattery, through the left-hand winding of relay 30. and sequence switchcontacts 220 (15) and (11 to 10) to conductor 67 thence both branchesextend by way of conductor 67 and M segment and corresponding brush ofthe line-finder commutator to ground. Relay '30 in operating closes abranch path to ground for n'iaintaining its energization, this pathextending from the right-hand Winding of relay 30, by way of sequenceswitch tator to ground.

Y contact of relay and contact 202 (15) of the finder sequence switch,right-hand front contact and armature of relay 30, sequence switchcontact 218 (15), conductor 67 and M segment and corresponding brush ofthe line-finder commu- The completion of this circuit energizes thefinder sequence switch 200 and causes it to move its cams to position16.

' In moving out of position 15 the sequence switch opens at its 220 cam,the branch ofthe energizing path that includes the lefthand winding ofrelay 30, and also opens the path to ground by way of.conductor 67 andthe M segment of the line-finder commutator; the energization of therelay being maintained in position 16 of the sequence switch by way ofthe branch that includes its right-hand winding, cam 216, left-handcontacts of relay 30, and resting contacts of relay 37. This circuit isheld closed and relay 30 is kept energized until the cord circuitthrough which the call was extended has returned to its normalcondition. When this occurs a clrcuit is closed that extends x (9 to 17)and (16), and winding of relay 37 to ground. The closure of this circuitenergizes relay 37, which attracts its armature and opens thepreviously-traced holding circuit of the relay 30. 'Relay 30in releasingits armatures closes a circuit that extends from battery through thewindin of downdrive magnet 62 of the line-finder switch, conductor 60,sequence switch contacts 223 (16 to 7) and (16 to 16%), left-hand backcontact and armature of relay 30, and armature and back contact of relay37 to ground (the energizing circuit of relay 37 having been interruptedat the right-hand front contact and armature of relay 30 when that relayreleased). :As a result of the closure of this circuit, the brushes ofthe line-finder switch are returned to normal.

-It will be noted that the circuit-for energizing the down-drive magnet62 of the line nder is not closed until relay 30 has been released as aresult of the energization of relay 37, and that relay 37 is notreleased until the circuit by way of conductor 88 of the connecting co rd circuit is closed by the complete return of the connecting cordcircuit to its normal condition. As a result of this arrangement it ispossible, by holding the connecting cord circuit and preventing theclosure of listening key sequence switch contact 406 (1), to hold thebrushes of the line-finder switch in engagement with the terminals ofthe calling line, even after the act of disestablishing the connectionhas been initiated by the release of the holding relay 30 andthemovement of the finder sequence switch out of the talking position 14.This feature is desirable where, for instance, the relay30 of the findercircuit is accident ally released immediately after the finder circuitis extended to a connecting circuit, and before connection with thecalled line is completed. In this case, when the operator answers inresponse to the flashing of the lamp 161, she finds that the callingsubscriber is not conne ted with the circuit, the finder sequence switchhavin moved out of the talking position 14 and fiaving come to rest inposition 16. As the energizing circuit of the down-drive magnet 62 ofthe line finder cannot be closed in position 16 until conductor 88 isclosed at sequence switch contact 406' (1) by the return of thelistening key sequence switch to normal, the operator is able, byholding the listening key sequence switch in position 7, to prevent thereturn of the line finder until the switchboard attendant has beennotified and hasv identified the finder circuit that has failed tooperate properly. When this'has been done, the connection may bereleased and the line finder switch permitted to return to normal bycausing the listening key sequence switch to move to position 1 andclose, at contact 406 (1), the circuit of conductor 88. The operator mayaccomplish thisby press ing'the listening-out key 432,- which closes acircuit for moving the listening key sequence switch out of position 7.The switch moves through position 15 on account of the energizingpathfor its motor magnet completed by way of sequenceswitch contact .402(15), outer left-hand back contact and armature of relay 500, and lowerback contact and armature of relay 421, and comes to rest in position 1.

As the line-finder brushes reach normal, a circuit is closed thatextends from battery through the motor magnet and contact 204 i (16) ofthe finder sequence switch, conductor 69, and Y segment andcorresponding brush of the line-finder commutator to ground. When-thefinder sequence switch moves to position 17, as a result of the closureof the above traced circuit, a circuit is completed that extends frombattery through the winding of the down-drive magnet 35 of the cordselector, conductor 90, finder sequence switch contact 218 (17 conductor67, and M segment and corresponding brush of the line finder commutatorto ground. The closure of this circuit returns the cord selector switchto normal; and as the brushes reach'normal a circuit is closed thatextends from battery through the wind- I process of establishing ordisestablishing a 52 opens the path over which" and 94 correspondingwith the connection is as has been described in the foregoing. It may,however, occasionally happen in the operation of'the system that forsome reason, line relay 12 or the failure of the cut-ofl relay 11 tooperate, that the high potential test battery which identifies thecalling line is not removed from the finder. switch test terminals ofthat line when.the line is con" nected with. The manner iii which thesystem is organized to care for this particular condition when it ariseswill now be described.

It will be remembered that when the finder switch makes connection withthe calling line the sequence switch 200 is moved out of position 4, andthat when the sequence switch reaches position 4;}, a circuit is closedby way of cam 212 and conductors 50 and 53 for energizing the cut-offrelay 11 of calling line and bringing about the release of theassociated line relay 12. If for any reason the line relay fails torelease its armatures, the high potential identifying battery 251remains in connection with the test conductor'253 of the associatedline. Consequently when the finder-sequence switch moves out of position6 upon the finder circuit gaining access to the operators selectingcircuit, a circuit is closed that extends from the high potential testbattery 251, the winding of the common protective relay 250, thearmature and back contact of that relay left-hand front contact andarmature of line relay 12, test conductor 253, test terminal 47 andcorresponding test brush 43 of the line-finder, conductor 51, contacts224 (1 to 8) and (6 to 8) of the finder sequence switch, conductor 260,and right-hand winding of relay 52 of the circuit to ground. Thereforethe presence of the test potential at atime when in the normal operationit should be. absent, causes the energization of the delay 52. Relay 52,in operating, closes a locking circuit for itself that extends frombattery through the left-hand winding of relay 52, left-handfrontcontact and armature of that relay, conductor 71, finder sequenceswitch contact 218 (6g to 8), conductor 67, and the M segment andcorresponding brush of the linefinder commutator to ground. At itsrighthand. armature and .back contactfthe relay the impulse of relays 93available operators'po'sition. Thus, when, an instant must fiow thatoperates the set such as the sticking of the operators selecting later,the finder sequence switch reaches position 7, the ground that isapplied to conductor 73 by the closure of finder sequence switchcontacts 218 (7 to 8) does not pass to one or another of the sets ofrelays 93 and winding of relay 30, contacts 220 (l to 13) and (7) of thefinder sequence switch to the same conductor 72. Thence the circuitcontinues by way of the right-hand front contact and armature of relay52, inner arma- 2 ture and front contact of the relay 54, back contactand armature of relay 63, back contact and armature of relay 61,conductor 73, finder sequence switch contact 218 (7), conductor 67, andsegment M and corresponding brush of the-line-finder commutator toground. Relay 30 attracts its armatures and closes a circuit thatextends from battery through the motor magnet and cam 202 (6 to 7) ofthe finder sequence switch, righthand front contact and armature ofrelay 30, contact 208 (2 to 7) of the finder sequence switch, conductor79, and segment M and corresponding brush of the cord selectorcommutator to ground. The closure of this circuit moves the findersequence switch to position 8. Relay 30 in operating also closes alocking circuit for itself that includes its right-hand winding andextends to ground by way of contact 216 (7 to 9) and (2 to 9) of thefinder sequence switch, left-hand front .contact and armature of relay30, and armature and back contact of the relay 37.

The movement of the" sequence finder switch to position 8 and theoperation of the relay 30, closes the circuit of the cord selectorupdrive magnet 34 in a manner that has already been described, and thebrushes of the'cord selector switch start to move up. .But as'theenergization of the relay 52 has prevented the operation of any of thesets of relays 93 and 94 of the operators selecting apparatus, none ofthe trip magnets 21, 22 is actuated, and consequently the sets ofbrushes are moved past the tripping position without any of the setsbeing tripped. As the tripping position is passed, the grounding of theK segment of the cord selector commutator completes the circuit forenergizing'the relay 61 of the operators selecting aliparatus, and thatrelay closes the circuit y way of contacts 204 (8) of the findersequence switch that causes the sequence switch to move out of position8 The circuit just and into position 9, as already described. Inposition 9 of the finder sequence swltch the upward movement of the cordselector brushes continues. But as none of the sets of brushes has beentripped to make it operative, the brush carrying rod or elevator goes tothe limit of its upward movement, and there grounds the X segment of thecord selector commutator. This closes a circuit that extends frombattery through the motor magnet and contacts 205 (7 to 14:) and (1 to16) of the finder sequence switch (the switch being in position 9 at thetime), conductor 70, and X segment and corresponding brush of the cordselector commutator to ground. As a result of the closure of thiscircuit the finder sequence switch is moved through its positions up toand including position 14, coming to rest in position 15.

In position 15 of the finder sequence switch an energizing circuit isclosed for both windings of the relay 30, one branch of this ener-.gizing circuit extending from battery through resistance 56, findersequence switch contacts 217 (15 to 16) and (12 to 16), righthandwinding of relay 30, and contacts 220 (15) and (11 to 16) of.the findersequence .switch to conductor 67, and the other branch extending frombattery through the lefthand winding of relay 30, finder sequence switchcontacts 220 (15) and (11 to 16) to the same conductor 67. Thence thepath is to ground by way of the M segment and corresponding brush of theline-finder commutator. Relay 30, in operating, closes a circuit foritself that includes its right-hand winding and extends through findersequence switch contacts 216 (15 to 16), left-hand front contact andarmature of relay 30, and armature and back contact of relay 37 toground. Relay 30 in operating also closes at its right-hand frontcontact and armature a circuit for moving the finder sequence switch outof position 15, as previously described.

In both positions 15 and 16 of the finder.

sequence switch a circuit is completed that extends from battery throughthe Windingof relay 255, finder sequence switch contacts 205 (15 to 16)and (1 to 16), conductor 70 and X segment and corresponding brush of thecord selector to ground. Relay 255 in operating closes at its upperarmature and front contact an energizing circuit for the lamp 257, andthe illumination of the lamp indicates to the switchboard attendant thata cord selector switch is at tell-tale; that is, that its brushes havepassed beyond the selectable contacts and are at the limit of theirupward movement. The attendant thereupon may inspect the cord selectorsof the associated frame, note the selector switch that is at tell-tale,ascertain the number of the line upon which the brushes of the correary31, 1916;

tery through the winding of the down-drive magnet 62 of the associatedline finder, conductor 60, finder sequence swltch contacts 223 (16 to6%), right front contact and armature of relay 255, and the closedcontacts of switch 256 to ground. The closure of this circuit restoresthe line-finder to its normal position. The grounding of the Y segmentof the line-finder commutator when the brushes are returned moves theline-finder sequence switch out of position 16 and into position 17, themovement of the finder SQ- "quence switch into position 17 closes theenergizing circuitof the down-drive magnet 35 of the cord selector, andthe return of the cord selector brushes to their normal position groundsthe Y segment of the cord selector commutator and moves the findersequence switch to its normal or 1 position, all as has heretofore beendescribed in connection with a normal operation of the organization.

From the foregoing it may be seen that the organization is such thatwhen, through any improper operation of the apparatus, the testpotential is not removed from the calling line when that line isconnected with, the finder circuit is immediately deprived of anycontrol over the operators selecting circuit and the corresponding cordselector switch is moved to tell-tale and a signal 'ven the switchboardattendant, the cord selector being held at tell-tale and the associatedline-finder being held on the terminals of the calling line ifthe switch256 is open, and thefinder circuit and switches being automaticallyreturned to normal if the switch 256 is closed. The failure of the linerelay to release is thus prevented from extending the line that is introuble to an operators position.

In order that the features to which this invention is directed may befully and clearly disclosed, it has been necessary to describe them inconnection with other features that are the subject of copendingapplications assigned to same assignee, such applications including theapplications of S. B. Williams, Jr., Serial No. 75,328, filed January31, 1916; Serial No. 75,329, filed Janu- Serial No. 107,090, filed July1, 1916, and the application of F. A. Steal-n. Serial No. 107,540, filedJuly 5, 1916. Such other features are the subject of claims in theapplications mentioned above, and are not claimed in the presentapplication.

calling line in establishing connection there with, operator selectingapparatus associated with said finder circuit a test magnet responsiveto the altered'electrical conditionof a connected telephone line, andmeans controlled in the response of said test magnet for rendering saidoperator selecting apparatus inoperative.

. 2. The combination with a plurality of telephone lines, of a source oftest current, means associated with each line for connecting said sourcewith said line in calling, a finder circuit responsive to said testcurrent for making connection with the calling line,

means for disconnecting said source from said calling line inestabllshing connectlon therewith, selecting apparatus controlling afurther extension of said finder circuit, a

test magnet associated therewith responsive to a continuance of saidcurrent on the calling line after the finder circuit has estab-' lishedconnection therewith, and means controlled in the response of said testmagnet for rendering said selecting apparatus inoperative.

3. The combination with a plurality of finder circuits, of a pluralityof operators positions common selecting apparatus. controlling theextension of said finder circuits to said operators positions, a testmagnet associated with said common selecting apparatus for rendering thesame temporarily.

inoperative, a source of current for operating said test magnet, andmeans for bringing. said source into connection with said test magnet byway of any of said finder circuits when such circuit is in abnormalcon.-

dition, whereby an abnormal condition of a finder circuit prevents thesame from selecting an operator. 7 a

4. The combination with a plurality of telephone lines, of a pluralityof operators V positions, a plurality of finder circuits forestablishing connection between any line and any operators position,common selecting apparatus controlling the extension of a finder circuitto an operators position, a test magnet for rendering said commonselecting apparatus temporarily inoperative, a source of current foroperating said test magnet, and means rendered operative by an abnormalcondition of any connected line for applying said source .to said testmagnet.

5. The combination with a plurality of operators positions, of aplurality of circuits adapted to be extended thereto, selectingapparatus common to said circuits and said positions, saidselectingapparatus actmg to control the extension of any of saldclrcults to any operators positlon, a source of current, means operatingunder abnormal conditions for applying said source of current to any ofsaid circuits, and means responsive to the application of said source ofcurrent to any said circuits for rendering said common selectingapparatus temporaany connected line for operating the aforesaidpreventing means.

7. The combination with a plurality of telephone lines, of afinder'circuit for making connection therewith, a plurality ofconnecting circuits, a switch for extendingthe connection of said findercircuit to an idle one of said connecting circuits, means for preventingsaid switch from extending the connection of said finder circuit, andmeans for actuating said preventing means made operative by an abnormalcondition of any line connected with said finder circuit.

8. The combination with a plurality of telephone lines and a pluralityof connecting circuits, of a finder circuit provided with a finderswitch for making connection with any of said telephone lines and a. selector switch for making connection with any of said connectingcircuits, a source of test current, means for applying the same to anyof said lines in calling, means actuated in establishing connection witha calling line for withdrawing said source of test current, and meansresponsive to thereontinuance of said test current on a calling lineafterconnection is made therewith for preventing said selector'switchfrom establishing connection with any of said connecting circuits.

9. The combination with a telephone line, of a source of test current,means for connecting said source with said line'in calling, a findercircuit providedwith a finderjswitch responsive to said source of testcurrent to establish connection with a calling line, means operated inestablishing connection for disconnecting said source of test fcurrent,means for further extending said finder circuit, and means operated bythe continued connection of said source with said line after the finderswitch has connected therewith for preventing'the operation of saidcircuit extending means.

10. The -combination with a telephone line, of means for altering theelectrical condition of the same in calling, a finder circuit responsiveto the altered "condition of said calling line for making connectiontherewith, means operated in .establishing ing circuit, means forextending said finder.

circuit to said' connecting circuit, and means responsive to thecontinuation of the altered electrical condition of said line afterconnection is made therewith for preventing the operation of saidextending means.

11. The combination with a telephone line, of means for altering theelectrical condition of the same in calling, a finder circuit responsiveto the altered condition of said calling line for making connectiontherewith, means operated in establishing said connection for restoringthe, normal electrical condition of said line, a connecting circuit, aswitch for connecting said finder circuit with said connecting circuit,an emergency device, and means responsive to the continuation of thealtered electrical condition of said line after connection is madetherewith for preventing said switch from extending said finder circuitto said connecting circuit and causing it to operate said emergencydevice.

12. The combination with a telephone line and a cord circuit, of afinder circuit, a switch for connecting said finder circuit with saidtelephone line, means for connecting said finder circuit with said cordcircuit, a sequence switch associated with and controlling said cordcircuit, means actuated in connecting said finder circuit with said cordcircuit for moving said sequence switch out of its normal position, andmeans made operative by the return of said sequence switch for movingsaid finder switch to disconnect said finder circuit from said telephoneline.

1%. The combination with a telephone line and a cord circuit, of afinder circuit,

means for connecting said finder circuit with said telephone line, meansfor connecting said finder circuit with said cord circuit, a sequenceswitchassociated with and controlling said cord circuit, means ac-'tuated 1n connectlng sa1d finder clrcul't with said cord circuit formoving said sequence switch out of its normal position, means forreturning said sequence switch to normal, and means made operative bythe return of said sequence switch for disconnecting said finder circuitfrom said cord circuit.

14. The combination with a calling telephone line, a connecting circuit,and a finder circuit uniting the same, of a sequence switch associatedwith said connecting circuit, means actuated by the completion ofconnection between said findercircuit and sa1d connecting c1rcu1tfor'moving said sequence switch out of normal, a called telephone line,necting circuit with said called line, :1

means for connecting said conswitch operated in disconnecting saidconnecting circuit from said called line for returning said sequenceswitch to normal, and means actuated by the return to normal of saidsequence switch for disconnecting said finder circuit from said callingline.-

' 15. The combination with a telephone line and a .connecting circuit,of a finder circuit for uniting the same, testing'mechanism responsiveto the normal electrical condition of said connecting circuit, meanscontrolled thereby for causing the finder circuit to make connectionwith said connecting circuit means for varying the electrical conditionof said connecting circuit responsive to the establishment of connectiontherewith, means for reestablishing the normal electrical condition ofsaid connecting circuit, and means made. operative by said testingmechanism upon the reestablishment of said normal electrical conditionfor efi'ecting the disconnection of said finder circuit from saidtelephone line.

1-6. The combination with a connecting circuit, of a finder circuit, anelectromagnetic switch for establishing connection between said findercircuit and said connecting circuit, a test magnet controlling theoperation of said switch, said test magnet being responsive to thenormal electrical condition of said connecting circuit, means operatingto Vary the electrical condition of said connecting circuit upon theestablishment of connection therewith, means for re.-

' electromagnetic line-connecting switch, and

an electromagnetic cord-connecting switch,

means for varying the electrical condition of any of said lines and ofany of said cords, a test magnet associated with said finder circuit,means controlledby said test magnet in response to the changedelectrical condition of a line for causing said line-connecting switchto establish connection there- .with, means controlled by said testmagnet in responseto the normal electrical condition of a cord forcausing said cord-connecting switch to establish connection therewithand vary the electrical condition of the same, means'for reestablishingthe normal electrical condition of the cord, and means controlled bysaid test magnet in response

